Marelli engine.....What goes where?


I use an XJ-S engine on my E Type. The car I ve got did not have any engine.
The V12 is a Marelli one. I ve a problem to fit back all the hoses, delay valve and other solenoid valve…
Can someone with the same engine supply pictures ?

(BobPhx) #2

Maybe some of these are useful, most are pretty high res and you can zoom in.

(Steve) #3

Are you saying that you’ve transplanted the engine and ALL electronics from the donor XJS into your E-type?

If you’re NOT running the fuel injection system (LUCAS) and the ignition system (Marelli) and have reverted back to carbs, most of the hoses can be eliminated.

Also, if the donor car came via the US, there will be a LOT of emissions system stuff that was not needed in Europe and other parts of the World in the late 80s and early 90s. And there are a lot of vacuum lines and solenoids that are part of the latter system…

(Michael Garcia) #4

check what yhe host vehicles’ computer needs,
cut out,
see what it survives on…


Hi Steve,
Thank you for your feedback.
I use the entire engine + the management ecus for both fuel and ignition through the 2 amplifiers and coils.
My concern is “just” the solenoid valve and the delay valve.
The solenoid valve has three possibe conections. I dont know which hoses have to be plugged on.
Same for the delay valve.
Do you have pictures of your own configuration?


Hi Bob
Great pictures and beautiful job done!
Do you have pictures from the solenoid (blue) valve from the right side under the air filter?
Cheers Michel

(BobPhx) #7

I the pics I posted (and just deleted) are on my site so you would have seen those… I don’t know of anything that is “blue” in under the right air filter except perhaps for the air pump bypass solenoid thingy which is not on my car…?

(baxtor) #8

I have an 89 UK spec. marelli with that valve. I will check it out and post hookup layout.
Won’t be able to get pic under there though.

(Steve) #9

You must be talking about the secondary air injection components pictured here:

#5 is the switchover solenoid ( EAC7905 ), located near the A-bank throttle body of my 6.0L. It is blue.

If I were you, I’d remove the air-injection pump and all the components associated with the system, Not needed for your E-type.


Here is the valve I m talking about:

Steve, it looks like the drawing you have posted.
Do you know where goes the hose “2”?
I dont recognize the “1” part. Can you let me know What is it and do you have the part number.
What is the use of this valve ?

(baxtor) #11

Valve looks very similar to mine. “1” is not fitted to my car but that line is vacuum to marelli ECU.
“2” runs to throttle edge tapping on top of throttle body and remaining connection (tube in foreground your pic) is on spigot at crossover pipe connection at rear or R/H manifold.
Looking at your pic l also see rubber hose where l would expect to see water rail???


Hi Baxtor
Your feedback helps. I still dont know what is this valve for.
Your right there is a rubber hose instead of a metallic tube. Half of the water rail is from the e type, the front one and the rear is from the xjs.

(Steve) #13

I am not sure you see/read all my posts. I explained already what the blue solenoid under the A-bank throttle body is for. Here:

Let’s try again:

This system should be completely redundant for your e-type and all components should be removed (you never told us where did you get the donor XJS engine from)

(Steve) #14

“1” and “2” might be a reference to the diagram I posted here:

Unless Jaguar did something completely different for markets other than the US, I don’t see how vacuum to the ECU can be controlled via solenoids (which are turned on/off via the ECU itself).

Or, the engine vacuum for 5.3L vs 6.0L is absolutely different (which I also have hard time understanding).

With regard to this, my 6.0L has another solenoid in this general area, which is part of the hot-start system (basically the ECU shuts off the vacuum line to the ECU and when the engine is hot, the fuel pressure is not modulated by the manifold vacuum for a pre-set period of time).

Here is the complete diagram from the Jaguar manual: